Effects-heavy family comedy Evan Almighty topped the North American box office chart for the weekend, opening with an estimated gross of $32.1m. But it was Stephen King horror adaptation 1408 that impressed most, with its $20.2m debut.

The weekend's other wide release, fact-based drama A Mighty Heart, opened slightly below expectations with an estimated $4m. Michael Moore's documentary Sicko, meanwhile, grabbed an estimated $70,000 from a single screen in a hastily arranged sneak preview.

Evan Almighty , produced for Universal Pictures by Spyglass Entertainment, took its $32.1m from 3,604 theatres, for a per-theatre average of $8,910.

The pricey (reportedly $175m) sequel to 2003's Bruce Almighty, again directed by Tom Shadyac but with Steve Carell starring instead of the original's Jim Carrey, got mostly negative reviews and was not expected to match Bruce's $68m three-day opening figure. But with its PG rating (Bruce was PG-13) and perceived appeal to religious audiences - Carell's title character is asked by God to become a new Noah -- it was expected by some pundits to achieve an opening closer to $40m.

1408 , the Weinstein Company's psychological thriller adapted from a King short story, came in second, taking its estimated $20.2m ($20,175,000 without rounding) from 2,678 theatres, for an average of $7,534.

With John Cusack and Samuel L Jackson starring for Swedish director Mikael Håfström, the film, distributed domestically by MGM, got strong reviews and stood out from the recent glut of gory but under-performing horror offerings.

A Mighty Heart , the true story of the search for slain journalist Daniel Pearl by his wife Mariane, opened at 1,355 theatres and grossed just over $4m (for an average of $2,956), ending up in tenth place on the chart.

Produced by Plan B and Revolution Films for distributor Paramount Vantage, with Angelina Jolie and Dan Futterman starring and Michael Winterbottom directing, the drama was well received by critics and attracted a lot of publicity. Its serious subject matter, though, made it a tricky sell to summer audiences.

The new releases were helped by a steeper than expected drop for last week's number one, Fox's Fantastic Four: Rise Of The Silver Surfer. The comic book-based sequel fell 65% (more than its predecessor's second-weekend drop) to an estimated $20.15 from 3,963 theatres, for a $5,085 average and a total to date of $97.6m.

Warner's Ocean's Thirteen, last week's number two, dropped 42% to $11.3m from 3,450 theatres (average - $3,290), for a $91m total.

Universal's Knocked Up was the holdover star, though, slipping just 24% to $10.6m from 2,975 theatres (average - $3,575). That pushed the comedy's domestic total past the century mark to $109m.

After opening in seventh spot last week, Warner's Nancy Drew held on well, sliding 34% to $4.5m from 2,612 theatres (average - $1,723), for a $16.2m total.

Outside the top ten, Sicko, the Michael Moore documentary from Lionsgate and the Weinstein Company, opened in a single New York theatre (and in the same late-June slot as Moore's 2004 smash Fahrenheit 9/11) as a prelude to its wide domestic release next weekend. The film, about health care in the US, has already attracted plenty of publicity and showed its potential by taking an estimated $70,000.

Next weekend's wide releases are: Buena Vista/Pixar's animated Ratatouille, from director Brad Bird, with Patton Oswalt leading the voice cast; Fox's belated Bruce Willis action sequel Live Free or Die Hard (aka Die Hard 4.0), directed by Len Wiseman, which opens on Wednesday; and, on around 900 screens, Focus Features' drama Evening, with Vanessa Redgrave, Natasha Richardson and Toni Collette starring for director Lajos Koltai.

Estimated Top 10 North America June 22-24, 2007

Film (Distributor)/International distribution/Estimated weekend gross/Estimated total to date

1 (-) Evan Almighty (Universal) UPI $32.1m -

2 (-) 1408 (MGM) Weinstein Co $20.2m -

3 (1) Fantastic Four: Rise Of The Silver Surfer (Fox) Fox Int'l $20.15m $97.6m

4 (2) Ocean's Thirteen (Warner Bros) WBPI $11.3m $91.0m

5 (3) Knocked Up (Universal) UPI $10.6m $109.0m

6 (4) Pirates Of The Caribbean: At World's End (Buena Vista) BVI $7.2m $287.0m

7 (5) Surf's Up (Sony) SPRI $6.7m $47.3m

8 (6) Shrek The Third (Paramount) PPI $5.8m $307.9m

9 (7) Nancy Drew (Warner Bros) WBPI $4.5m $16.2m

10 (-) A Mighty Heart (Paramount Vantage) PPI $4.0m -